A disk clamper has an internal magnet for attracting a magnetic body or the like mounted on a turntable, in order that the disk clamper and the turntable hold the disk by sandwiching the disk therebetween. Therefore, the disk clamper is so constructed that a clamper main body and a lid body hold the magnet or the like therebetween. Such a disk clamper is disclosed in Japanese Laid-Open Patent Publication No. 10-308047 (pages 3 to 4 and FIG. 1).
In the conventional disk clamper, a cylindrical member (a lid cylinder) provided on the lid body is fitted in the inside of a cylindrical member (a holding cylinder) provided on the clamper main body. Claws are integrally formed on a cylindrical wall of the lid cylinder, and the claws are deformable in the radial direction of the lid cylinder. The holding cylinder has engaging holes that engage the tips of the claws. In order to assemble the disk clamper, the lid cylinder is pushed into the inside of the holding cylinder in the axial direction. In this state, the claws of the holding cylinder first deform inwardly, and then engage the engaging holes of the holding cylinder. Because of the engagement of the claws and the engaging holes, the clamper main body and the lid body are integrated with each other.
Recently, in order to meet the demand for a thinner disk drive device, the lengths of the claws are set to approximately from 3 mm to 4 mm. If the lengths of the claws are short as above, large stresses are generated at the bases of the claws when the claws deform. In order to reduce the stresses at the bases of the claws to less than or equal to the allowable stress of component material (plastic), the claws are made thin, or the amounts of the deformations of the claws are reduced (i.e., the claws and the engaging holes slightly engage with each other).
However, if the thicknesses of the claws are made thin, or if the claws and the engaging holes slightly engage each other, it is not possible to obtain a sufficient coupling strength between the clamper main body and the lid body. Therefore, if an impact force is applied to the clamper main body and the lid body in the direction in which the clamper main body and the lid body separate from each other when the disk drive device is dropped or the like, the claws may be damaged or the claws may disengage from the engaging hole, with the result that the lid body and the clamper main body may separate from each other and may dropped from the turntable.
Moreover, for the disk clamper, it is required that the performance does not vary even if the assembling and disassembling of the disk clamper are repeated. However, when the disk clamper is disassembled, there is a possibility that the claws may be excessively deformed so that the claws may be broken at the bases thereof.